This biography of John Cockcroft focuses on his years working as a nuclear physicist, leader in the field of nuclear energy, and nuclear policy advisor to to the British government. Cockcroft became a Nobel laureate with Ernest Walton for their groundbreaking experiment which proved Einstein’s theory of mass and energy and led to the pursuit of fission as a source of energy. Cockcroft’s later years were largely consumed by his leadership of the Harwell research institute and work on the development of uranium power plants, before he returned to Cambridge to be a college Master in 1959. One of the authors of the book, T. E. Allibone, knew Cockcroft personally from the time when they were students together at the Cavendish Laboratory. The book is illustrated with black and white photographs.